Degradable material time delay system and method

ABSTRACT

A time delay tool and method includes a mechanical restraining element, a reservoir for containing a reactive fluid, an actuating device and a wellbore device. When a stored energy is applied on the wellbore device, the actuation device is actuated and enables the reactive fluid in the reservoir to come in contact with the mechanical restraining element. While the mechanical restraining element undergoes a change in shape due to a chemical reaction, a stored energy applied on the wellbore device is delayed by a pre-determined time delay. The amount of the pre-determined time delay is determined by factors that include the reactive fluids, concentration of the reactive fluids, geometry and size of the mechanical restraining element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/053,417, filed Feb. 25, 2016, the disclosure of which is fullyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to downhole wellbore tools.Specifically, the invention attempts to utilize a known fluid thatreacts with a degradable mechanical element permitting a known timedelay between a trigger event and a functional event.

PRIOR ART AND BACKGROUND OF THE INVENTION Prior Art Background

In oil and gas extraction applications, there is a need to have acertain length of time delay between pressure triggered events such thatthe system can be tested at a pressure before the next event couldproceed. This system cannot be controlled with any other means besidesthe application of pressure. Prior art system means of fluid restrictionuses a complex system of microscopic passages that meter fluid.Therefore, there is a need for non-expensive simple and flexiblecomponent flow restriction systems.

Inside a tandem in a gun string assembly, a transfer happens between thedetonating cords to detonate the next gun in the daisy chained gunstring. Detonation can be initiated from the wireline used to deploy thegun string assembly either electrically, pressure activated or byelectronic means. In tubing conveyed perforating (TCP) as there is noelectric conductor, pressure activated percussion initiation is used todetonate. TCP is used to pump up to a tubing pressure that reaches acertain pressure enabling a firing head to launch a firing pin.Subsequently, the firing pin starts the percussion initiator whichstarts the detonation cord. There is a need to delay the launching of afiring pin by a predetermined time in certain instances so that testscan be conducted or a hang fire condition may be detected on a previousgun.

In tandem systems there is a single detonating cord passing through theguns. There are no pressure barriers. However, in select fire systems(SFS) there is a pressure isolation switch between each gun. Each gun isselectively fired though its own detonation train. A detonator feeds offeach switch. When the lower most perforating gun is perforated, pressureenters the inside of the gun. When the first gun is actuated, the seconddetonator gets armed when the pressure in the first gun switch movesinto the next position actuating a firing pin to enable detonation inthe next gun. All guns downstream are isolated from the next gun by thepressure barrier.

Spool valves are directional control valves that are used as wellboretools. They allow fluid flow into different paths from one or moresources. They usually consist of a spool inside a cylinder which ismechanically or electrically controlled. The movement of the spoolrestricts or permits the flow, thus it controls the fluid flow. Thereare two fundamental positions of directional control valve namely normalposition where valve returns on removal of actuating force and other isworking position which is position of a valve when actuating force isapplied. However, prior art spool valves do not have a control mechanismwith a pre-determined delay to switch from normal position to a workingposition.

It is known that well fluids vary in the chemical nature and are notalways the same composition. However, the temperature of the well isoften defined or can be manipulated to achieve a pre-determinedtemperature. Most time delay elements currently used comprise complexmechanisms and are often expensive. Therefore, there is a need for atime delay tool that can use a known fluid or an unknown fluid inside awell at a known temperature such that a known degradable element canreact and degrade in the known fluid at the known temperature for aknown amount of time so that a pre-determined time may be achieved totrigger a mechanism in a device.

Deficiencies in the Prior Art

The prior art as detailed above suffers from the following deficiencies:

-   -   Prior art systems do not provide for a known degradable element        that can react and degrade in a known fluid at a known        temperature for a known amount of time so that a pre-determined        time may be achieved to trigger a mechanism in a device.    -   Prior art systems do not provide for a low cost configurable        time delay flow restriction element that is commonly available.    -   Prior art systems do not provide for a predictable time delay.    -   Prior art systems do not provide for a cost effective time delay        solution that are independent of the wellbore fluids.    -   Prior art systems require bulky and expensive hydraulics.    -   Prior art systems require expensive electronics that have        difficulty functioning at downhole temperatures.

While some of the prior art may teach some solutions to several of theseproblems, the core issue of a predictable time delay with known fluidsat pre-determined temperatures has not been addressed by prior art.

BRIEF SUMMARY OF THE INVENTION System Overview

The present invention in various embodiments addresses one or more ofthe above objectives in the following manner. The tool includes amechanical restraining element, a reservoir for containing a reactivefluid, an actuating device and a wellbore device. When a stored energyis applied on the wellbore device, the actuation device is actuated andenables the reactive fluid in the reservoir to come in contact with themechanical restraining element. While the mechanical restraining elementundergoes a change in shape or strength due to a chemical reaction, astored energy applied on the wellbore device is delayed by apre-determined time delay. The amount of the pre-determined time delayis determined by factors that include the reactive fluids, concentrationof the reactive fluids, geometry and size of the mechanical restrainingelement.

Method Overview

The present invention system may be utilized in the context of anoverall time delay method, wherein the downhole wellbore time delay toolas previously described is controlled by a method having the followingsteps:

-   -   (1) positioning the wellbore tool at desired wellbore location;    -   (2) applying stored energy on the wellbore device;    -   (3) actuating the actuating device and enabling fluid        communication between the mechanical restraining element and the        reactive fluid;    -   (4) initiating a chemical reaction between the mechanical        restraining element and the reactive fluid;    -   (5) progressing the chemical reaction for a pre-determined time        delay and altering size of the mechanical restraining element;    -   (6) releasing restraint by the mechanical restraining element;        and    -   (7) triggering a movement in the wellbore device.

Integration of this and other preferred exemplary embodiment methods inconjunction with a variety of preferred exemplary embodiment systemsdescribed herein in anticipation by the overall scope of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the advantages provided by the invention,reference should be made to the following detailed description togetherwith the accompanying drawings wherein:

FIG. 1 illustrates a cross-section overview diagram of downhole wellboretime delay tool according to an exemplary embodiment of the presentinvention.

FIG. 2 illustrates a cross-section overview diagram of downhole wellboretime delay tool with an energetic device and a firing pin according toan exemplary embodiment of the present invention.

FIGS. 3A-3D illustrates a cross-section view of downhole wellbore timedelay tool with an energetic device and a firing pin describing aninitial set up, actuation position, a degradation position, and atriggering position according to an exemplary embodiment of the presentinvention.

FIGS. 3E-3H illustrates a cross-section view of downhole wellbore timedelay tool with an energetic device and a firing pin with a shear pinrestraint describing an initial set up, actuation position, adegradation position, and a triggering position according to anexemplary embodiment of the present invention.

FIG. 4A illustrates a perspective view of a downhole wellbore time delaytool with an energetic device and a firing pin according to an exemplaryembodiment of the present invention.

FIG. 4B illustrates a perspective view of a downhole wellbore time delaytool with an energetic device and a firing pin with a shear pinrestraint according to an exemplary embodiment of the present invention.

FIGS. 5A-5D illustrates a cross-section view of downhole wellbore timedelay tool with an energetic device and a firing pin and a spring loadeddevice describing an initial set up, actuation position, a degradationposition, and a triggering positions according to an exemplaryembodiment of the present invention.

FIG. 6 illustrates a perspective view of a downhole wellbore time delaytool with an energetic device and a firing pin and a spring loadeddevice according to an exemplary embodiment of the present invention.

FIGS. 7A-7D illustrates a cross-section view of downhole wellbore timedelay tool with a spool valve describing an initial set up, actuationposition, a degradation position, and a triggering positions accordingto an exemplary embodiment of the present invention.

FIGS. 7E-7F illustrates a cross-section view of downhole wellbore timedelay tool with a spool valve and a tensile member according to anexemplary embodiment of the present invention.

FIG. 8 illustrates a perspective view of a downhole wellbore time delaytool with a spool valve according to an exemplary embodiment of thepresent invention.

FIGS. 9A-9D illustrates a cross-section view of downhole wellbore timedelay tool with a firing pin and a switch describing an initial set up,actuation position, a degradation position, and a triggering positionaccording to an exemplary embodiment of the present invention.

FIG. 10 illustrates a perspective view of a downhole wellbore time delaytool with a firing pin and a switch according to an exemplary embodimentof the present invention.

FIG. 11 illustrates a cross section view of a downhole wellbore timedelay tool with a dissolvable plug according to an exemplary embodimentof the present invention

FIG. 12 illustrates an exemplary flow chart for a time delay methodoperating in conjunction with a downhole wellbore time delay toolaccording to an embodiment of the present invention.

FIG. 13 illustrates a preferred exemplary flowchart embodiment of a timedelay firing method in conjunction with a downhole wellbore time delaytool that is integrated into an energetic device used in TCP operationaccording to an embodiment of the present invention.

FIG. 14 illustrates an exemplary Time vs Temperature curve forcalculating a time delay based on a known fluid and known restrainingelement according to an embodiment of the present invention.

FIG. 15 illustrates an exemplary predictable time delay flowchartoperating in conjunction with a predictable downhole time delay toolaccording to an embodiment of the present invention.

OBJECTIVES OF THE INVENTION

Accordingly, the objectives of the present invention are (among others)to circumvent the deficiencies in the prior art and affect the followingobjectives:

-   -   Provide for a known degradable element that can react and        degrade in a known fluid at a known temperature for a known        amount of time so that a pre-determined time may be achieved to        trigger a mechanism in a device.    -   Provide for a low cost configurable time delay flow restriction        element that is commonly available.    -   Provide for a predictable time delay.    -   Provide for a cost effective time delay solution that is        independent of the wellbore fluids.    -   Provide for a tubing conveyed perforating gun with a delay        mechanism which provides a known delay interval between        pressuring the tubing to a second predetermined level and the        actual firing of the perforating gun.    -   Provide for a delay means to move a firing pin holder out of        locking engagement with a firing pin, to release firing pin,        after a predetermined time interval.    -   Provide for portable and inexpensive hydraulics for a time delay        tool.    -   Provide for an inexpensive time delay tool that functions        reliably at downhole temperatures.    -   Provide for a time delay tool suitable for wireline conveyed,        coil tubing conveyed, casing conveyed or pump down.

While these objectives should not be understood to limit the teachingsof the present invention, in general these objectives are achieved inpart or in whole by the disclosed invention that is discussed in thefollowing sections. One skilled in the art will no doubt be able toselect aspects of the present invention as disclosed to affect anycombination of the objectives described above.

Description of the Presently Preferred Exemplary Embodiments

While this invention is susceptible of embodiment in many differentforms, there is shown in the drawings and will herein be described indetailed preferred embodiment of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit the broadaspect of the invention to the embodiment illustrated.

The numerous innovative teachings of the present application will bedescribed with particular reference to the presently preferredembodiment, wherein these innovative teachings are advantageouslyapplied to the particular problems of a hydraulic time delay system andmethod. However, it should be understood that this embodiment is onlyone example of the many advantageous uses of the innovative teachingsherein. In general, statements made in the specification of the presentapplication do not necessarily limit any of the various claimedinventions. Moreover, some statements may apply to some inventivefeatures but not to others.

Preferred Exemplary Downhole Wellbore Time Delay Tool Integrated into anEnergetic Device (0200-0600)

As generally illustrated in FIG. 1 and FIG. 2 (0200), a downholewellbore time delay tool (0210) for use in a wellbore casing comprises areservoir (0211) for containing a reactive fluid (0201), an actuatingdevice (0202) such as a rupture disk, a mechanical restraining element(0203) such as a nut and mechanically connected to a wellbore devicesuch as an energetic device (0220) with firing pin (0204), a percussioninitiator (0205), a booster (0206) and a detonating cord (0207). Adetailed view of the wellbore tool (0210) is illustrated in FIG. 1. Theentire tool (0200) may be piped into the casing string as an integralpart of the string and positioned where functioning of the tool isdesired or the tool may be deployed to the desired location with TCP, CTor a wire line. The wellbore may be cemented or not. The fluid in thereservoir (0211) is held at an initial position by the actuating device(0202), such as a rupture disk. The tool mandrel is machined to acceptthe actuating device (0202) (such as rupture discs) that ultimatelycontrols the flow of reactive fluid (0201). The fluid reservoir (0211)may be further installed in within a fluid holding body (0208). Thefluid holding body (0208) may be operatively connected to a body (0209)of the energetic device (0220). In one embodiment, the rated pressure ofthe actuating device may range from 500 PSI to 15000 PSI.

The reservoir (0211) may be in fluid communication with the mechanicalrestraining element via the actuation device (0202). Alternatively, thereactive fluid may be directly in fluid communication with themechanical restraining element via the actuation device (0202) without areservoir. For example, the mechanical restraining element may not be influid communication initially with any fluid. When the pressure in thewellbore casing increases to actuate the actuating device, wellborefluids may enter and react with the mechanical restraining element. Itshould be noted that the reservoir to contain a reactive fluid may notbe construed as a limitation. A pressure port (0213) may be attached toanother end of the reservoir through another actuating device (0212).The reservoir (0211) may be a holding tank that may be positioned insidea fluid holding body (0208) of a well casing. The volume of thereservoir may range from 25 ml to 5 liters. The material of thereservoir may be chosen so that the reactive fluid inside the reservoirdoes not react with the material of the reservoir and therefore does notcorrode or erode the reservoir (0211). According to a preferredexemplary embodiment, the material of the reservoir may be selected froma group comprising: metal, ceramic, plastic, degradable, long termdegradable, glass, composite or combinations thereof. The reservoir mayalso be pressurized so that there is sufficient flow of the reactivefluid towards the restraining element. The actuation device (0202) maybe a reverse acting rupture disk that blocks fluids communicationbetween the reactive fluid and the restraining element. The actuationdevice (0212) ruptures or actuates when a pressure in the wellborethrough the pressure port (0213) exceeds a rated pressure of theactuating device (0212). After the actuating device (0212) rupture, thepressure acting through the pressure port (0213) may act on the fluidwhich further acts on the actuating device (0202). When the pressure ofthe fluid acting on the actuation device (0202) exceeds a rated pressureof the actuating device (0202), the reactive fluid (0201) flows throughand enters a chamber and comes in contact with the restraining element(0203). According to another preferred exemplary embodiment theactuating device is an electronic switch that is actuated by a signalfrom a device storing a stored energy.

The pressure on the actuation device (0202) may be ramped up to therated pressure with pressure from the reactive fluid. The reactive fluid(0201) is configured to react with the mechanical restraining element(0203) at a temperature expected to be encountered in the wellbore.According to a preferred exemplary embodiment a physical property changein the restraining element may occur at a pre-determined temperatureexpected to be encountered in the wellbore casing. According to afurther preferred exemplary embodiment the pre-determined temperatureranges from 25° C.-250° C. The mechanical restraining element (0203) maybe a nut, a shear pin, or a holding device that degrades as the reactiontakes place. Upon further degradation, the mechanical restrainingelement (0203) may release a restraint on the energetic device (0220)and enable the entire pressure or stored energy to act on an end of theenergetic device (0220).

According to a preferred exemplary embodiment the reactive fluid isselected from a group comprising: fresh water, salt water, KCL, NaCl,HCL, or hydrocarbons.

The energetic device (0220) may be operatively connected to themechanical restraining element via threads, seals or a connectingelement. The tool mandrel may be machined to accept the wellborereservoir, the actuating device and the wellbore device such as a firingpin assembly. In some instances, the mechanical restraining element maybe a nut that may be screwed or attached to a counterpart in thewellbore device. In other instances the restraining element may be atensile member. The wellbore device may be an energetic device (0220)with a firing pin (0204) as illustrated in FIG. 2 (0200).

According to a preferred exemplary embodiment, when a stored energy,such as a pressure from a fluid, is applied on the firing pin assembly,the actuating device (0202) is actuated and the reactive fluid (0201)from the reservoir (0211) comes into contact with the mechanicalrestraining element (0203) and enables a physical property change in themechanical restraining element such that the stored energy applied onthe wellbore device is delayed by a pre-determined time delay while themechanical restraining element undergoes the physical property change.The physical property change may enable the restraining element tochange shape for a pre-determined period of time. The physical propertymay be strength, ductility or elasticity. In tubing conveyed perforatinggun with a delay mechanism, a known delay interval between pressuringthe tubing to a second pre-determined level and the actual firing of theperforating gun may be achieved by the pre-determined time delay. In aselect fire system, a delay means, to move a firing pin holder out oflocking engagement with a firing pin to release the firing pin, may beachieved by the predetermined time interval. 5. The firing pin (0204)may contact a percussion detonator/initiator (0205) that connects to abidirectional booster (0206). The bidirectional booster (0206) mayaccept a detonation input from the detonator. The detonating cord (0207)may be initiated in turn by the booster (0206). When the firing pin isactuated after the mechanical restraint (0203) is released, the firingpin (0204) may contact a percussion detonator (0205) and in turninitiate a detonator through a booster (0206) and a detonating cord(0207).

According to a preferred exemplary embodiment, the stored energy isapplied from a spring. According to another preferred exemplaryembodiment, the stored energy is applied from a pressure from a fluidand a seal. According to a further preferred exemplary embodiment, thestored energy is applied from a magnetic field. According to yet anotherpreferred exemplary embodiment, the stored energy is applied from aweight.

According to a preferred exemplary embodiment, the pre-determined timedelay ranges from 1 hour to 48 hours. According to a more preferredexemplary embodiment, the pre-determined time delay ranges from 2 daysto 14 days. According to a most preferred exemplary embodiment, thepre-determined time delay ranges from 0.01 seconds to 1 hour.

According to a preferred exemplary embodiment, the chemical reaction maybe an exothermic reaction that gives off heat. The energy needed toinitiate the chemical reaction may be less than the energy that issubsequently released by the chemical reaction. According to anotherpreferred exemplary embodiment, the chemical reaction may be anendothermic reaction that absorbs heat. The energy needed to initiatethe chemical reaction may be greater than the energy that issubsequently released by the chemical reaction.

The rate of the chemical reaction may be accelerated or retarded basedon factors such as nature of the reactants, particle size of thereactants, concentration of the reactants, pressure of the reactants,temperature and catalysts. According to a preferred exemplaryembodiment, a catalyst may be added to alter the rate of the reaction.According to a preferred exemplary embodiment, the material of therestraining element may be selected from a group comprising: mixture ofaluminum, copper sulfate, potassium chlorate, and calcium sulfate, iron,magnesium, steel, plastic, degradable, magnesium-iron alloy, particulateoxide of an alkali or alkaline earth metal and a solid, particulate acidor strongly acid salt, or mixtures thereof. The catalyst may be selectedfrom a group comprising salts. According to a preferred exemplaryembodiment, the material of the restraining element may be selected froma group comprising: metal, non-metal or alloy.

According to a preferred exemplary embodiment the mechanical restrainingelement is a restrictive plug element. For example, the restriction plugelement may be a ball or a plug that is used to isolate pressurecommunication between zones or stages in a well casing.

According to a preferred exemplary embodiment the pre-determined timedelay is determined by concentration of the reactive fluids. Accordingto another preferred exemplary embodiment the pre-determined time delayis determined by reaction rate of the reactive fluids with themechanical restraining element. According to yet another preferredexemplary embodiment the pre-determined time delay is determined byreaction time of the reactive fluids with the mechanical restrainingelement. According to a further preferred exemplary embodiment thepre-determined time delay is determined by masking a contact area of themechanical restraining element. According to a further preferredexemplary embodiment the pre-determined time delay is determined bymasking a total area of the mechanical restraining element in contactwith the mechanical restraining element.

According to a preferred exemplary embodiment the shape of themechanical restraining element is selected from a group comprising:square, circle, oval, and elongated.

A sealed cap may seal the exposed end of the reservoir to physicallyprotect the reservoir from undesired wellbore conditions.

According to an alternate preferred embodiment, a multi stagerestraining element comprising a blocking member and a restrainingmember may further increase a time delay. For example, mechanicalrestraining element (0203) may be coupled with a blocking member thatmay have a different composition and reaction time with the fluid in thereservoir. The blocking member may react with the fluid for a period oftime and may restrict fluid access to the mechanical restraining elementfor a pre-determined period of time. It should be noted that the multistage restraining element may not limited to a blocking member and arestraining element. Any number of blocking members and restrainingelements may be used in combination to achieve a desired time delay. Thereaction times and therefore the time delays of each of the bondingmembers with the fluid may be characterized at various temperaturesexpected in the wellbore.

In another preferred exemplary embodiment, the reservoir may be filledwith wellbore fluids. For example, the reservoir may be empty whendeployed into the wellbore and later filled with wellbore fluids. A timevs temperature chart for the restraining element may be characterizedwith different compositions of wellbore fluids expected in the wellboreat temperatures expected in the wellbore casing. Alternatively, thefluid reservoir may be partially filled with the known fluid andwellbore fluids may fill the remaining portion of the reservoir. Thereservoir may be filled with the known fluid, wellbore fluids or acombination thereof. The mechanical restraining element may comprise oneor more material types that react and have different degradation ratesin one or more fluid types. The desired time delay may be achieved witha combination of fluid types and restraining element material types.

The present exemplary embodiment is generally illustrated in more detailin FIG. 3A (0300), FIG. 3B (0310), FIG. 3C (0320), FIG. 3D (0330),wherein the downhole wellbore delay tool is deployed inside a wellborecasing. FIGS. 3A-3D generally illustrates different positions of afiring pin assembly (0304). The positions include an initial set upposition (0300), an actuation position (0310), a degradation position(0320) and a triggering position (0330). The entire tool may be pipedinto the casing string as an integral part of the string and positionedwhere functioning of the tool is desired. In one exemplary embodiment,the tool may be a firing pin assembly that is positioned wheredetonation, perforation of a formation and fluid injection into aformation is desired. The tool may be installed in either direction withno change in its function. A detailed view of the tool in the initialset up position is shown in FIG. 3 (0300) where in the fluid in thereservoir is held by the actuating device (0302). When ready to operate,the pressure is increased for example with TCP. The tool then moves tothe actuation position (0310), when pressure acting on the actuatingdevice (0302) exceeds its rated pressure, the actuation device rupturesand enables reactive fluid in the fluid reservoir (0301) to enter theadjacent chamber and contacts the restraining element. Subsequently,after elapse of a pre-determined time delay, the restraining elementdegrades or changes shape due to the chemical reaction as illustrated inthe degradation position in FIG. 3C (0320). In the triggering position(0330), the firing pin (0304) in the energetic device is triggered asthe restraining element (0303) no longer holds or restrains the firingpin (0304) due to change of shape or strength. The entire stored energymay be applied to move the firing pin and contact a bidirectionalbooster, after the pre-determined time delay in the degradationposition. The stored energy may be applied by pressure and seal,magnetic field, a weight, a spring or combination thereof.

FIG. 4A (0400) generally illustrates a perspective view of the downholedelay tool with a firing pin as the wellbore device.

Similar to FIGS. 3A-3D, a downhole delay tool with a firing pin and ashear pin restraint is generally illustrated in FIGS. 3E-3H. Asgenerally illustrated in more detail in FIG. 3E (0350), FIG. 3F (0360),FIG. 3G (0370), FIG. 3H (0380), wherein the downhole wellbore delay toolis deployed inside a wellbore casing. FIGS. 3E-3H generally illustratesdifferent positions of a firing pin assembly (0324) restrained by ashear pin (0325) in addition to a mechanical restraining element (0323).The positions include an initial set up position (0350), an actuationposition (0360), a degradation position (0370) and a triggering position(0380). A detailed view of the tool in the initial set up position isshown in FIG. 3E (0350) wherein the fluid in the reservoir is held bythe actuating device (0322). When ready to operate, the pressure isincreased for example with TCP. The tool then moves to the actuationposition (0360), when pressure acting on the actuating device (0322)exceeds its rated pressure, the actuation device ruptures and enablesreactive fluid in the fluid reservoir (0321) or well fluids from thewellbore casing to enter the adjacent chamber and contacts therestraining element. Subsequently, after elapse of a pre-determined timedelay, the restraining element degrades or changes shape due to thechemical reaction as illustrated in the degradation position in FIG. 3G(0370). In the triggering position (0380), the firing pin (0324) in theenergetic device is triggered as the restraining element (0323) nolonger holds or restrains the firing pin (0324) and the shear pin (0325)due to change of shape or a physical property. According to a preferredexemplary embodiment, the shear pins provide additional control, whenthe time delay enables, but it would need an active input to finallyfire. FIG. 4B (0410) generally illustrates a perspective view of thedownhole delay tool with an energetic device and a firing pin and ashear pin restraint mechanism as the wellbore device. The mechanicalrestraining element (0323) could be degraded, releasing the shear pin(0325), and then the tool would have to be pumped to a pressuresufficient to shear the shear pins (0325), which would allow the firingpin (0324) to strike a percussion initiator (not shown).

Similar to FIGS. 3A-3D, a downhole delay tool with a firing pin and aspring is generally illustrated in FIGS. 5A-5D. As generally illustratedin more detail in FIG. 5A (0500), FIG. 5B (0510), FIG. 5C (0520), FIG.5D (0530), wherein the downhole wellbore delay tool is deployed inside awellbore casing. FIGS. 5A-5D generally illustrates different positionsof a firing pin assembly (0504) restrained by a spring (0505). Thepositions include an initial set up position (0500), an actuationposition (0510), a degradation position (0520) and a triggering position(0530). A detailed view of the tool in the initial set up position isshown in FIG. 5A (0500) wherein the fluid in the reservoir is held bythe actuating device (0502). When ready to operate, the pressure isincreased for example with TCP. The tool then moves to the actuationposition (0510), when pressure acting on the actuating device (0502)exceeds its rated pressure, the actuation device ruptures and enablesreactive fluid in the fluid reservoir (0501) to enter the adjacentchamber and contacts the restraining element. Subsequently, after elapseof a pre-determined time delay, the restraining element degrades orchanges shape due to the chemical reaction as illustrated in thedegradation position in FIG. 5C (0520). In the triggering position(0530), the firing pin (0504) in the energetic device is triggered asthe restraining element (0503) no longer holds or restrains the firingpin (0504) and the spring (0505) due to change of shape or a physicalproperty. FIG. 6 (0600) generally illustrates a perspective view of thedownhole delay tool with an energetic device and a firing pin and aspring loading mechanism as the wellbore device.

Preferred Exemplary Downhole Wellbore Time Delay Tool Integrated with aSpool Valve (0700-0800)

Similar to FIGS. 3A-3D, a downhole delay tool with a spool valve isgenerally illustrated in FIGS. 7A-7D. A detailed view of the tool in theinitial set up position is shown in FIG. 7A (0700) wherein the fluid inthe reservoir is held by the actuating device (0702) and a sleeve (0704)may block ports (0705, 0706) and disable pressure or fluid communicationto a hydrocarbon formation. When ready to operate, the pressure isincreased for example with TCP. The tool then moves to the actuationposition (0710), when pressure acting on the actuating device (0702)exceeds its rated pressure, the actuation device ruptures and enablesreactive fluid in the fluid reservoir (0701 to enter the adjacentchamber and contacts the restraining element (0703). Subsequently, afterelapse of a pre-determined time delay, the restraining element degradesor changes shape due to the chemical reaction as illustrated in thedegradation position in FIG. 7C (0720). In the triggering position(0730), a movement in a sleeve (0704) in the spool valve is triggered asthe restraining element (0703) no longer holds or restrains the sleeve(0704) due to change of shape. After being released from the restrainingelement, the sleeve (0704) may slide and unblock one or more ports(0705, 0706) and enable pressure or fluid communication to a hydrocarbonformation. Similar to the mechanical restraining element (0703) in FIG.7A (0700), a tensile member (0713) is generally illustrated in FIG. 7E(0740). The tensile member (0713) may react with a reactive fluid from areservoir (0711) and provide a time delay for the tensile member (0713)to break and enable a sleeve in the spool valve to slide and open ports(0714, 0715). FIG. 7F (0750) generally illustrates a sleeve positionafter the ports (0714, 0715) are opened to the hydrocarbon formation.FIG. 8 (0800) generally illustrates a perspective view of the downholedelay tool with a spool valve and a sliding sleeve as a wellbore device.

Preferred Exemplary Downhole Wellbore Time Delay Tool Integrated with aPin and a Switch (0900-1000)

Similar to FIGS. 3A-3D, a downhole delay tool with a pin and a switch isgenerally illustrated in FIGS. 9A-9D. As generally illustrated in moredetail in FIG. 9A (0900), FIG. 9B (0910), FIG. 9C (0920), FIG. 9D(0930), wherein the downhole wellbore delay tool is deployed inside awellbore casing. FIGS. 9A-9D generally illustrate different positions ofa firing pin assembly (0904) and a switch (0906) with a contact (0905).The positions include an initial set up position (0900), an actuationposition (0910), a degradation position (0920) and a triggering position(0930). A detailed view of the tool in the initial set up position isshown in FIG. 9A (0900) where in the fluid in the reservoir is held bythe actuating device (0902). In the initial set up position (0900), theelectrical contact may not be connected to the pin (0904). When ready tooperate, the pressure is increased for example with TCP. The tool thenmoves to the actuation position (0910), when pressure acting on theactuating device (0902) exceeds its rated pressure, the actuation deviceruptures and enables reactive fluid in the fluid reservoir (0901) toenter the adjacent chamber and contacts the restraining element (0903).Subsequently, after elapse of a pre-determined time delay, therestraining element degrades or changes shape due to the chemicalreaction as illustrated in the degradation position in FIG. 9C (0920).In the triggering position (0930), the pin (0904) in the wellbore deviceis triggered as the restraining element (0903) no longer holds orrestrains the pin (0904) due to change of shape or a physical property.The movement of the pin enables the pin to complete an electricalconnection that may be used to trigger an electrical event for purposesof perforating or determining a status. FIG. 10 (1000) generallyillustrates a perspective view of the downhole delay tool with a pin anda switch as the wellbore device.

Preferred Exemplary Downhole Wellbore Time Delay Tool Integrated with aDegradable Restriction Element (1100)

FIG. 11 (1100) generally illustrates a degradable restriction element(1103) blocking a flow channel (1104) in a wellbore casing. A knownreactive fluid may be provided to react with the degradable restrictionelement (1103). After an elapse of a predictable time period, thedegradable restriction element (1103) may degrade or change physicalshape to enable fluid communication through the channel (1104).

Preferred Exemplary Flowchart Embodiment of a Time Delay Method (1200)

As generally seen in the flow chart of FIG. 12 (1200), a preferredexemplary flowchart embodiment of a time delay method may be generallydescribed in terms of the following steps:

-   -   (1) positioning a wellbore tool at a desired wellbore location        (1201);        -   The entire tool may be piped into the casing string as an            integral part of the string and positioned where functioning            of the tool is desired or the tool may be deployed to the            desired location using TCP, Coiled tubing (CT) or a wire            line. The wellbore may be cemented or not. The wellbore tool            and the wellbore device may be deployed separately or            together.    -   (2) applying stored energy on the wellbore device (1202);        -   The stored energy may be applied by pressure and seal,            magnetic field, a weight, a spring or combination thereof.            The energy may be transferred via TCP or wireline. The            stored energy may be directly applied via the restraining            element. The stored energy may be applied indirectly via an            actuating device and pressure.    -   (3) actuating the actuating device and enabling contact between        the mechanical restraining element and the reactive fluid        (1203);        -   If the differential pressure acting on the piston is greater            than a rated pressure of a pressure activated opening            device, the device ruptures and allows the piston to move.            The rating of the pressure activated device could range from            5000 PSI to 15000 PSI.    -   (4) initiating a chemical reaction between the mechanical        restraining element and the reactive fluid (1204);        -   According to a preferred exemplary embodiment the            pre-determined time delay is determined by composition of            the reactive fluids. According to another preferred            exemplary embodiment the pre-determined time delay is            determined by reaction rate of the reactive fluids with the            mechanical restraining element. According to yet another            preferred exemplary embodiment the pre-determined time delay            is determined by reaction time of the reactive fluids with            the mechanical restraining element. According to a further            preferred exemplary embodiment the pre-determined time delay            is determined by masking a contact area of the mechanical            restraining element.    -   (5) progressing the chemical reaction for a pre-determined time        delay and altering size of the mechanical restraining element        (1205);        -   According to a preferred exemplary embodiment, the            pre-determined time delay ranges from 1 hour to 48 hours.            According to a more preferred exemplary embodiment, the            pre-determined time delay ranges from 2 days to 14 days.            According to a most preferred exemplary embodiment, the            pre-determined time delay ranges from 0.01 seconds to 1            hour.    -   (6) releasing restraint on the wellbore device by the mechanical        restraining element (1206); and        -   the mechanical restraint may be a nut that decreases in size            or loses threads and grip, thereby releasing the wellbore            device.    -   (7) triggering the wellbore device (1207).        -   The triggering step (7) may move a piston in the wellbore            device. The triggering step (7) may open a port in the            wellbore device. The triggering step (7) may unplug a            wellbore device. The triggering step (7) may enable a            rotational movement in the wellbore device.

Preferred Exemplary Flowchart Embodiment of a Time Delay Firing Method(1300)

As generally seen in the flow chart of FIG. 13 (1300), a preferredexemplary flowchart embodiment of a time delay firing method inconjunction with a downhole wellbore time delay tool; the downholewellbore time delay tool integrated into an energetic device used in TCPoperation may be generally described in terms of the following steps:

-   -   (1) positioning a downhole wellbore time delay tool at a desired        wellbore location (1301);        -   The entire tool may be piped into the casing string as an            integral part of the string and positioned where functioning            of the tool is desired or the tool may be deployed to the            desired location using TCP or a wire line. The wellbore may            be cemented or not. The downhole wellbore time delay tool            may be a tool (0210) as aforementioned in FIG. 2 (0200).    -   (2) increasing pressure to actuate an actuating device (1302);        -   The pressure may be applied through TCP or the wellbore            pressure may be pumped out until the actuating device such            as a rupture disk ruptures.    -   (3) initiating a chemical reaction between a mechanical        restraining element and a reactive fluid in the wellbore time        delay tool (1303);    -   (4) progressing the chemical reaction for a pre-determined time        delay and altering physical property of the mechanical        restraining element (1304);        -   According to a preferred exemplary embodiment, the            pre-determined time delay ranges from 1 hour to 48 hours.            According to a more preferred exemplary embodiment, the            pre-determined time delay ranges from 2 days to 14 days.            According to a most preferred exemplary embodiment, the            pre-determined time delay ranges from 0.01 seconds to 1            hour.    -   (5) bleeding pressure until optimal conditions for perforation        is reached (1305); and bleeding pressure creates a balanced or        an underbalanced condition for perforation.    -   (6) firing the wellbore device when the change in the physical        property in the mechanical restraining element releases a firing        pin in the energetic device (1306).        -   the mechanical restraining element may be a nut that            decreases in size or loses threads and grip, thereby            releasing the wellbore device. Alternatively, the mechanical            restraining element may be a shear pin, a tensile member or            a seal.

Preferred Exemplary Time vs Temperature Reaction Curve Embodiment (1400)

A time (1401) vs temperature (1402) reaction curve is generallyillustrated in FIG. 14 (1400). The nature of the curve depends on theknown fluid type reacting with a material of a mechanical restrainingelement. For example, curve (1410) may represent a fluid type “A”reacting with a material “A” of a mechanical restraining element, curve(1420) may represent a fluid type B reacting with a material “B”, andcurve (1430) may represent a fluid type “C” reacting with a material“C”. The reactive fluid may be a known fluid such as fresh water, saltwater, KCL, NaCl, HCL, oil, hydrocarbon or combination thereof. Thefluid may be contained in a reservoir (0211) as illustrated in FIG. 2.The mechanical restraining element may be a nut (0203) as illustrated inFIG. 2. The material of the mechanical restraining element may be ametal, a non-metal or an alloy. For example the material of themechanical restraining element may be Aluminum, Magnesium or analuminum-Magnesium alloy. A curve may be drawn for each combination of aknown fluid and a known material. A model may be developed from thecurve in order to calculate a time delay when a temperature isdetermined in a wellbore. For example, at a temperature of 180° F. thetime delay for curve (1410) may be 4 minutes (1411). Similarly, the timedelay for curve (1420) may be 20 minutes (1412) and time delay for curve(1430) may be 74 minutes (1413). A model may be developed for eachcombination of a known fluid and material. The model may be stored andused to determine a time delay when a temperature is determined in awellbore casing. The predictability of time delay based on a measuredtemperature enables a triggering event to be delayed reliably with agreater accuracy. Any time delay may be achieved by changing thecombination of the reactive fluid and material of the restrainingelement. The reservoir may be filled with the known fluid, wellborefluids or a combination thereof. The mechanical restraining element maycomprise one or more material types that react and have differentdegradation rates in one or more fluid types. The desired time delay maybe achieved with a combination of fluid types and restraining elementmaterial types. The mechanical restraining element may be used incombination with a shear pin mechanism as illustrated in FIGS. 3E-3H sothat additional control may be provided before a detonator can finallyfire. According to a preferred exemplary embodiment, a predictabledownhole time delay tool for determining time delay may comprise a knownfluid and a known mechanical restraining element wherein the known fluidis configured to react with the mechanical restraining element; and thetime delay is determined based upon a condition encountered in thewellbore when the known fluid reacts with the mechanical restrainingelement. According to another preferred exemplary embodiment, the timedelay is further based on a pre-determined reaction curve between theknown fluid and said the mechanical restraining element. According toyet another preferred exemplary embodiment, the wellbore condition iswellbore temperature. According to yet another preferred exemplaryembodiment, the wellbore temperature is determined by distributedtemperature sensing. The known fluid may be wellbore fluids that aresampled and characterized for time delay and temperature. The knownfluid may be contained in a reservoir or an open chamber configured topermit fluid to interact with a restraining element.

Preferred Exemplary Flowchart Embodiment of a Time Delay Firing Method(1500)

As generally seen in the flow chart of FIG. 15 (1500), a preferredexemplary flowchart embodiment of a predictable time delay method, themethod operating in conjunction with a predictable downhole time delaytool comprising a known fluid and a known mechanical restraining elementmay be generally described in terms of the following steps:

-   -   (1) positioning the wellbore time delay tool at a desired        wellbore location (1501);        -   The wellbore time delay tool may be deployed with TCP, CT, a            slick line, a wire line or pumped from the surface.    -   (2) determining a wellbore condition at the wellbore location        (1502); and        -   A wellbore condition such as a temperature may be determined            with known methods. For example, a fiber optic cable run            with the wellbore casing may be used to determine the            temperature. Other wellbore conditions such as wellbore            pressure, composition of the wellbore fluids may also be            determined using know methods and tools.    -   (3) calculating a time delay based on the wellbore condition        (1503).        -   A time delay may be calculated with a Time vs Temperature            curve as illustrated in FIG. 14 (1400). A triggering event            may be initiated in a wellbore device in the wellbore after            elapse of said time delay. The triggering event may be the            release of a firing pin to initiate a percussion primer to a            detonation train. Another trigger event may be unplugging a            restriction in a wellbore casing. Yet another triggering            event may be sliding a piston to open a port to establish a            connection to a hydrocarbon formation.

System Summary

The present invention system anticipates a wide variety of variations inthe basic theme of time delay, but can be generalized as a downholewellbore time delay tool for use with a wellbore device in a wellborecasing, comprising:

-   -   (a) a mechanical restraining element;    -   (b) a reactive fluid, said reactive fluid configured to react        with the mechanical restraining element;    -   (c) an actuating device configured to enable fluid communication        between the reactive fluid and the mechanical restraining        element;    -   whereby,    -   when a stored energy is applied on the wellbore device, the        actuating device actuates and the reactive fluid comes in        contact with the mechanical restraining element and initiates a        chemical reaction; the chemical reaction enables a physical        property change in the mechanical restraining element such that        the stored energy applied on the wellbore device is delayed by a        pre-determined time delay while the mechanical restraining        element undergoes the physical property change.

This general system summary may be augmented by the various elementsdescribed herein to produce a wide variety of invention embodimentsconsistent with this overall design description.

Method Summary

The present invention method anticipates a wide variety of variations inthe basic theme of implementation, but can be generalized as a downholewellbore time delay tool for use with a wellbore device in a wellborecasing, comprising:

-   -   (a) a mechanical restraining element;    -   (b) a reactive fluid, said reactive fluid configured to react        with the mechanical restraining element;    -   (c) an actuating device configured to enable fluid communication        between the reactive fluid and the mechanical restraining        element;    -   wherein the method comprises the steps of:    -   (1) positioning the wellbore tool at desired wellbore location;    -   (2) applying stored energy on the wellbore device;    -   (3) actuating the actuating device and enabling fluid        communication between the mechanical restraining element and the        reactive fluid;    -   (4) initiating a chemical reaction between the mechanical        restraining element and the reactive fluid;    -   (5) progressing the chemical reaction for a pre-determined time        delay and changing a physical property of the mechanical        restraining element;    -   (6) releasing restraint by the mechanical restraining element;        and    -   (7) triggering the wellbore device.

This general method summary may be augmented by the various elementsdescribed herein to produce a wide variety of invention embodimentsconsistent with this overall design description.

System/Method Variations

The present invention anticipates a wide variety of variations in thebasic theme of oil and gas extraction. The examples presented previouslydo not represent the entire scope of possible usages. They are meant tocite a few of the almost limitless possibilities.

This basic system and method may be augmented with a variety ofancillary embodiments, including but not limited to:

-   -   An embodiment wherein said tool is conveyed with said wellbore        casing.    -   An embodiment wherein said tool is deployed with a wireline        tool.    -   An embodiment wherein said tool is deployed with TCP.    -   An embodiment wherein said tool is pumped down with a pump down        tool.    -   An embodiment wherein the chemical change occurs at a        pre-determined temperature expected to be encountered in the        wellbore casing.    -   An embodiment wherein the pre-determined temperature ranges from        25° C.-250° C.    -   An embodiment wherein the reactive fluid is contained in a        reservoir.    -   An embodiment wherein the reactive fluid is selected from a        group comprising: fresh water, salt water, KCL, NaCl, HCL or        hydrocarbons.    -   An embodiment wherein the stored energy is applied from a        spring.    -   An embodiment wherein the stored energy is applied from a        pressure from a fluid and a seal.    -   An embodiment wherein the stored energy is applied from a        magnetic field.    -   An embodiment wherein the stored energy is applied from a        weight.    -   An embodiment wherein the time delay ranges from 1 hour to 48        hours.    -   An embodiment wherein the time delay ranges from 2 days to 14        days.    -   An embodiment wherein the delay time ranges from 0.01 seconds to        1 hour.    -   An embodiment wherein the actuating device is a rupture disk;        the rupture disk actuated by pressure in the wellbore casing.    -   An embodiment wherein the actuating device is an electronic        switch; the electronic switch actuated by a signal from a device        storing the stored energy.    -   An embodiment wherein the wellbore device is a firing pin; the        firing pin actuated when the mechanical restraining element        reacts with the reactive fluid and changes size.    -   An embodiment wherein the mechanical restraining element is a        nut.    -   An embodiment wherein the wellbore device is a spool valve; the        spool valve opens up a port when the mechanical restraining        element reacts with the reactive fluid and changes size.    -   An embodiment wherein the mechanical restraining element is a        tensile member.    -   An embodiment wherein the wellbore device is an electrical        switch; the electrical switch enables a connection when the        mechanical restraining element reacts with the reactive fluid        and changes size.    -   An embodiment wherein the mechanical restraining element is a        restrictive plug element.    -   An embodiment wherein the pre-determined time delay is        determined by composition of the reactive fluids.    -   An embodiment wherein the pre-determined time delay is        determined by reaction rate of the reactive fluids with the        mechanical restraining element.    -   An embodiment wherein the pre-determined time delay is        determined by reaction time of the reactive fluids with the        mechanical restraining element.    -   An embodiment wherein the pre-determined time delay is        determined by masking a contact area of the mechanical        restraining element.    -   An embodiment wherein the pre-determined time delay is        determined by masking a total area of the mechanical restraining        element in contact with the mechanical restraining element.    -   An embodiment wherein a shape of the mechanical restraining        element is selected from a group comprising: square, circle,        oval, and elongated.    -   An embodiment wherein a material of the mechanical restraining        element is selected from a group comprising: metal, non-metal,        alloy.    -   An embodiment wherein the reactive fluid is wellbore fluid        expected in the wellbore casing.

One skilled in the art will recognize that other embodiments arepossible based on combinations of elements taught within the aboveinvention description.

CONCLUSION

A time delay tool and method in a wellbore casing has been disclosed.The tool/method includes a mechanical restraining element, a reservoirfor containing a reactive fluid, an actuating device and a wellboredevice. When a stored energy is applied on the wellbore device, theactuation device is actuated and enables the reactive fluid in thereservoir to come in contact with the mechanical restraining element.While the mechanical restraining element undergoes a change in shape dueto a chemical reaction, a stored energy applied on the wellbore deviceis delayed by a pre-determined time delay. The amount of thepre-determined time delay is determined by factors that include thereactive fluids, concentration of the reactive fluids, geometry and sizeof the mechanical restraining element.

What is claimed is:
 1. A time delay method, the method using a wellboretime delay tool to delay action on a wellbore device, wherein the methodcomprises: after positioning said wellbore tool in a wellbore casing,activating an actuating device to enable fluid communication between amechanical restraining element and a reactive liquid such that achemical reaction takes place between the mechanical restraining elementand the reactive liquid, wherein the mechanical restraining element isdirectly attached to a firing pin of the wellbore device, the mechanicalrestraining element restrains the firing pin from moving, the reactiveliquid is stored in a volume within the wellbore time delay tool, thereactive liquid causes a physical change in the mechanical restrainingelement, and the actuating device is located between the volume and themechanical restraining element; releasing the restraint of themechanical restraining element on the firing pin of the wellbore deviceas a result of a time period of chemical reaction on the mechanicalrestraining element; and triggering the wellbore device as the firingpin moves due to a fluid pressure accumulated in the volume of thewellbore time delay tool.
 2. The time delay method of claim 1 whereinthe actuating device is a rupture disk and the step of activating theactuating device comprises bursting the rupture disk by a pressure inthe wellbore casing.
 3. The time delay method of claim 1 wherein thestep of triggering the wellbore device includes moving a piston.
 4. Thetime delay method of claim 1 wherein the step of triggering the wellboredevice includes opening a port.
 5. The time delay method of claim 1wherein the step of triggering the wellbore device includes unpluggingthe wellbore device.
 6. The time delay method of claim 1 wherein thestep of triggering the wellbore device includes causing a rotationalmovement of the wellbore device.
 7. The time delay method of claim 1wherein the time period for the chemical reaction in the step ofreleasing is a time delay for the step of triggering the wellboredevice, and the time delay is determined by a composition of thereactive liquid.
 8. The time delay method of claim 1 wherein the timeperiod for the chemical reaction in the step of releasing causes a timedelay between the step of activating and the triggering of the wellboredevice, and the time delay is determined by a reaction rate of thereactive liquid with said mechanical restraining element under downholeconditions.
 9. The time delay method of claim 1 wherein the time periodfor the chemical reaction in the step of releasing causes a time delaybetween the step of activating and the triggering the wellbore device,the time delay determined by a reaction time of the reactive liquid withthe mechanical restraining element.
 10. The time delay method of claim 1wherein the time period for the chemical reaction in the step ofreleasing causes a time delay between the step of activating and thetriggering of the wellbore device, the time delay determined by anextent of a masking off of a potential contact area of the mechanicalrestraining element with the reactive liquid.
 11. The time delay methodof claim 1 the step of activating the actuating device includes using anelectronic switch.
 12. The time delay method of claim 1 wherein the stepof activating the actuating device includes using a magnetic field. 13.The time delay method of claim 1 wherein the step of activating theactuating device includes using stored energy in a spring.
 14. The timedelay method of claim 1 wherein the step of activating the actuatingdevice includes using stored energy of a weight.
 15. A method of using awellbore time delay tool to delay a triggered action on a wellboredevice, the method of using the downhole time delay tool comprises thesteps of: after positioning the wellbore tool in a wellbore casing,rupturing a rupture disk to thereby enable fluid communication between amechanical restraining element and a reactive liquid such that achemical reaction takes place between the mechanical restraining elementand the reactive liquid, wherein the mechanical restraining element isdirectly attached to a firing pin of the wellbore device, the mechanicalrestraining element restrains the firing pin from moving, the reactiveliquid is stored in a volume within the wellbore time delay tool, thereactive liquid causes a physical change in the mechanical restrainingelement, and the rupture disk separates the volume from the mechanicalrestraining element; releasing the restraint of the mechanicalrestraining element on the firing pin of the wellbore device as a resultof a time period of chemical reaction on the mechanical restrainingelement; and triggering the wellbore device as the firing pin moves dueto a fluid pressure accumulated in the volume of the wellbore time delaytool.
 16. The method of claim 15, wherein the step of rupturing therupture disk comprises rupturing with a pressure in the wellbore casing.17. The method of claim 15 wherein the chemical reaction on themechanical restraining element triggers the firing pin.